Method and system for adaptive interleaving

ABSTRACT

A method a system for automatically controlling an adaptive interleaver involves monitoring performance parameters of a transmission system and controlling the adaptive interleaver in response to the performance parameters. The SNR and the data rate of the transmission system are preferably determined. The data rate is analyzed and the adaptive interleaver is adjusted in response to the data rate and the SNR. Alternatively, the BER and the data rate of the transmission system are determined. The data rate is analyzed and the adaptive interleaver is adjusted in response to the data rate and the BER. Alternatively, any one of the SNR, BER or data rate can alone be monitored and used to the adaptive interleaver. The system provides a effective system for adjusting an adaptive interleaver in response to performance parameters of a transmission system.

BACKGROUND

[0001] The present invention relates generally to transmission systemsand more specifically to adaptive interleavers.

[0002] Interleaving is a coding technique that is commonly used toincrease the performance of transmission systems by decreasing errors inthe system. Interleaving rearranges the data that is to be transmittedin a given transmission thereby improving the error-correctionperformance of redundancy coding techniques. Interleaving increases thetransmission latency of the interleaved transmissions. Latency is thetime required for data to traverse the end-to-end transmission path.

[0003] In most applications, the latency associated with interleaving isonly a small portion of the overall latency of the system. However, intelecommunications applications, and particularly with reference todigital subscriber lines, the latency associated with interleavingconstitutes a significant portion of the overall latency. High latencycan have a substantial negative impact on system performance especiallywhen the system is operating at high data transmission rates. The impactis especially pronounced for systems where many end-to-end transmissionsare required to accomplish a task, such as systems utilizing the popularTCP/IP data communications protocol to send a large file. Accordingly,telecommunications system providers generally strive to minimize latencythroughout their systems while still utilizing interleaving to offsetthe adverse effects of errors. Thus, it is desirable to optimize theinterleaving used such that only the degree of interleaving necessary toachieve a desired performance level is implemented.

[0004] Adaptive interleaving allows for different degrees ofinterleaving, commonly referred to as the interleave depth, to beapplied to different transmissions. Adaptive interleavers are known tothose skilled in the art. U.S. Pat. No. 4,901,319 describes an adaptiveinterleave system, including an adaptive interleaver, that attempts tocorrect errors that occur as a result of the fading characteristics of aradio channel. The system measures the phase error of transmissions inan effort to identify errors in the transmissions. The system utilizes acomplex system and method to predict the next error occurrence basedupon the measured phase error, and adjusts the adaptive interleaver inresponse to the prediction. However, measuring the phase error is not aneffective method for identifying errors in many transmission systems.Also, a complex system for predicting the occurrence of errors andcontrolling an adaptive interleaver can be difficult to implement onmany transmission systems.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005]FIG. 1 is a block diagram of the adaptive interleaver controllerof a first preferred embodiment.

[0006]FIG. 2 is a more detailed block diagram of the adaptiveinterleaver controller of FIG. 1.

[0007]FIG. 3 is a more detailed block diagram of the adaptiveinterleaver controller of FIG. 1

[0008]FIG. 4 is a more detailed block diagram of the adaptiveinterleaver controller of FIG. 1

[0009]FIG. 5 is a more detailed block diagram of the adaptiveinterleaver controller of FIG. 1

[0010]FIG. 6 is a more detailed block diagram of the adaptiveinterleaver controller of FIG. 1

[0011]FIG. 7 is a flow chart of a method for controlling an adaptiveinterleaver of a first preferred embodiment.

[0012]FIG. 8 is a flow chart of a method for controlling an adaptiveinterleaver of a second preferred embodiment.

[0013]FIG. 9. is a flow chart of a method for controlling an adaptiveinterleaver of a third preferred embodiment.

[0014]FIG. 10. is a flow chart of a method for controlling an adaptiveinterleaver of a fourth preferred embodiment.

[0015]FIG. 11 is a flow chart of a method for controlling an adaptiveinterleaver of a fifth preferred embodiment.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0016] The present embodiments provide an effective system forautomatically controlling an adaptive interleaver in response to theperformance parameters of a transmission system. Referring now to FIG.1, a controller 5 for determining one or more performance parameters andgenerating an adaptive interleave control signal in response to theperformance parameters is shown. The controller 5 preferably comprisesmeans 1 for analyzing input signals, means 2 for providing an adaptiveinterleave control signal, means 3 for determining a first performanceparameter and means 4 for determining a second performance parameter.The means 3 for determining a first performance parameter preferablycomprises a first performance parameter monitor for determining a firstperformance parameter and generating a first input signal as known tothose skilled in the art. The means 4 for determining a secondperformance parameter preferably comprises a second performanceparameter monitor for determining a second performance parameter andgenerating a second input signal as known to those skilled in the art.The performance parameters are preferably chosen from the groupconsisting of signal to noise ratio (SNR), bit error rate (BER) and datarate.

[0017] As illustrated in the following embodiments, the systempreferably determines the SNR and the data rate of the transmissionsystem. The data rate of the system is analyzed and the adaptiveinterleaver is adjusted in response to the data rate and the SNR.Alternatively, the bit error rate (BER) and the data rate of thetransmission system can be determined. The data rate of the system isanalyzed and the adaptive interleaver is adjusted in response to thedata rate and the BER. Alternatively, any one of the SNR, BER or datarate can alone be determined and used to control the adaptiveinterleaver. While such a system is of particular importance with regardto digital subscriber lines, those skilled in the art will appreciatethat it is applicable to any system that incorporates interleaving.

[0018] By way of example, FIG. 2 shows a transmission system 10comprising an adaptive interleaver 20, a transmitter 30, a transmissionchannel 35, a receiver/decoder 40 and a controller 50. The adaptiveinterleaver 20 interleaves data that is transmitted by the transmitter30 over the transmission channel 35. The receiver/decoder 40 receivesand decodes the interleaved data. The controller 50 determinesperformance parameters of the system in an effort to determine whetherinterleaving is beneficial and if it can be implemented. The controlleralso generates an adaptive interleave control signal 58 in response tothe performance parameters. The adaptive interleaver preferably adjuststhe interleave depth in response to the adaptive interleave controlsignal 58.

[0019] The adaptive interleaver 20 preferably comprises means forreceiving a multiple bit adaptive interleave control signal and meansfor adjusting the interleave depth in response to the adaptiveinterleave control signal as known to those skilled in the art. Theadaptive interleaver 20 preferably further comprises means foradaptively interleaving data at different interleave depths as known tothose skilled in the art. The adaptive interleaver 20 is preferablycoupled with the transmitter 30 and the controller 50. The phrase“coupled with,” as used herein, means coupled either directly orindirectly via one or more intervening elements. One example of anadaptive interleaver is shown in U.S. Pat. No. 4,901,319 which is herebyincorporated by reference.

[0020] The adaptive interleaver 20 preferably receives data andinterleaves the data by rearranging the order in which the bits thatcomprise the data are transmitted. The interleave depth is preferablydefined as the distance between bits that originally were adjacent toone another. The interleave depth is altered by varying the distancebetween originally adjacent bits. The data is preferably encoded throughthe use of coding techniques known to those skilled in the art before itis received by the adaptive interleaver 20. Alternatively, any suitableadaptive interleaver that is responsive to a multiple bit adaptiveinterleave control signal, as known to those skilled in the art, can beconfigured for use in the present embodiments.

[0021] The transmitter 30 preferably comprises an Asymmetric DigitalSubscriber Line (ADSL) transmitter as known to those skilled in the art.Alternatively, the transmitter 30 can comprise a digital transmitter foruse with any form of transmission media as known to those skilled in theart. Alternatively, the transmitter 30 can comprise any transmitter foruse with any form of transmission media as known to those skilled in theart. The transmitter 30 is preferably coupled with the adaptiveinterleaver 20, the data rate monitor 60 and the transmission channel35.

[0022] The transmitter 30 modulates data for transmission to thereceiver/decoder 40 via the transmission channel 35 as known to thoseskilled in the art. The transmitter 30 can preferably transmit data atdifferent data rates as known to those skilled in the art. The capacityof the transmission channel 35 is one common factor that can be used asa basis for adjusting the data rate. The capacity of the transmissionchannel 35 typically depends on factors including the following: thedistance a transmission has to travel; the wire gauge of thetransmission channel; the number of bridged-taps on the transmissionchannel; the temperature of the transmission channel, the splice loss ofthe transmission channel; noise present in the transmission channel; andthe precision of the transmitter and receiver. While many of thesefactors are not directly measurable, their cumulative effect may bemonitored by measuring one or both of the SNR and BER of the system.Thus, the data rate can be adapted in response to the SNR or BER.

[0023] The transmitter 30 typically adapts the data rate by altering thetime allowed for the transmission of a symbol comprising a number ofbits. Accordingly, a greater or lesser number of bits can be transmittedwithin a given time interval depending upon the alterations.Alternatively, the data rate can be altered by modulating a greater orlesser number of bits into each transmission. For example, increasingthe number of usable points in a Quadrature Amplitude Modulation (QAM)constellation results in the modulation of more bits in eachtransmission. When the data rate is increased through either of thesemethods, the SNR of the system is generally decreased. A decrease in theSNR generally results in an increase in the BER when the data rateincreases or is unchanged. Thus, to maintain a given BER, there is aupper limit for the data rate for a particular transmission channel.Accordingly, by monitoring the SNR and BER, the data rate can beadapted, through the use of the methods described above, to the maximumdata rate possible while maintaining an acceptable BER. The data ratecan be adapted once at system start-up, or continuously as known tothose skilled in the art.

[0024] The transmission channel 35 preferably comprises twisted-pairconductive wire as known to those skilled in the art. Alternatively, thetransmission channel can comprise coaxial cable, optical fiber,free-space laser, radio or any other type of transmission media as knownto those skilled in the art. The transmission channel 35 is preferablycoupled with the transmitter 30 and the receiver/decoder 40.

[0025] The receiver/decoder 40 preferably comprises an ADSL receiver, anadaptive de-interleaver and a sequential decoder as known to thoseskilled in the art. Alternatively, the receiver/decoder 40 can comprisea digital receiver/decoder for use with any type of transmission mediaas known to those skilled in the art. Alternatively, thereceiver/decoder 40 can comprise any type of receiver/decoder for usewith any type of transmission media as known to those skilled in theart. For example, the receiver/decoder 40 can employ a Reed Solomondecoder or any other suitable error correcting decoder as known to thoseskilled in the art. The receiver/decoder 40 is preferably coupled withthe transmission channel 35 and the signal to noise ratio monitor 70.

[0026] The receiver/decoder 40 receives and demodulates the data fromthe transmitter 30. After demodulation, the receiver/decoder 40de-interleaves the data and utilizes decoding techniques known to thoseskilled in the art to detect and correct errors in the data. Forexample, the receiver/decoder 40 can analyze data including redundantbits that are generated by an encoder prior transmission, to determinewhether any data was corrupted and thus requires correction.

[0027] The controller 50 preferably comprises a data rate monitor 60, asignal to noise ratio monitor 70, means 54 for analyzing input signalsand means 56 for providing an adaptive interleave control signal. Thedata rate monitor 60 preferably comprises a monitor for determining thedata rate of the system 10 as known to those skilled in the art. Thedata rate monitor 60 is preferably coupled with the transmitter 30 andthe controller 50. The data rate can be determined by counting thenumber of bits, bytes, symbols, blocks, frames, cells, or packets sentper time interval as known to those skilled in the art. Alternatively,the data rate can be inferred from the frequency of the master clocksignal used by the transmitter or from the symbol rate detected by thereceiver/decoder 40 as known to those skilled in the art. Alternatively,for manually controlled systems, the value in the data register holdingthe data rate that is set by the operator can be directly accessed bythe data rate monitor 60 to determine the data rate. Alternatively, thedata rate can be determined through a variety of other techniques, andany suitable method for determining the data rate can be adapted for usein the presently preferred system. Averaging many measurements of thedata rate can be performed to improve the accuracy of the current datarate calculations as known to those skilled in the art.

[0028] The data rate monitor 60 determines the data rate and generatesan input signal 68 that preferably varies as a function of the datarate. Alternatively, the input signal 68 can take many forms. The inputsignal 68 can be based in-whole or in-part on the data rate. The inputsignal 68 can be analog or digital and linear or non-linear as known tothose skilled in the art. Alternatively, the input signal 68 can bebinary such that input signal 68 is greater than or less than athreshold value based upon the data rate as known to those skilled inthe art. The data rate monitor 60 preferably determines the data rateand continuously generates the input signal 68. Alternatively, the datarate monitor 60 can determine the data rate and generate the inputsignal 68 in a sampled fashion on a random or non-random basis.

[0029] The signal to noise ratio monitor 70 preferably comprises amonitor for determining the SNR as known to those skilled in the art.The SNR monitor 70 is preferably coupled with the transmission channel35 and the controller 50. SNR is preferably defined as the ratio ofaverage signal power to average noise power. The signal power can bedetermined by measuring the maximum amplitude and phase deviation of allreceived data prior to demodulation. The noise power can be determinedby measuring the amplitude and phase distance between adjacent points inthe modulation constellation as known to those skilled in the art.Alternatively, the SNR can be determined through a variety of othertechniques, and any suitable method of determining the SNR can beadapted for use in the presently preferred system. Averaging manymeasurements of SNR can be performed to improve the accuracy of thecurrent SNR calculations as known to those skilled in the art.

[0030] The signal to noise ratio monitor 70 preferably determines theSNR and generates an input signal 78 that varies as a function of theSNR. Alternatively, the input signal 78 can take many forms. The inputsignal 78 can be based in-whole or in-part on the SNR. The input signal78 can be analog or digital and linear or non-linear as known to thoseskilled in the art. Alternatively, the input signal 78 can be binarysuch that the input signal 78 is greater than or less than a thresholdvalue based upon the SNR as known to those skilled in the art. The SNRmonitor 70 preferably determines the SNR and continuously generates theinput signal 78. Alternatively, the SNR monitor 70 can determine the SNRand generate the input signal 78 in a sampled fashion on a random ornon-random basis.

[0031] The means 54 for analyzing input signals preferably comprisesmeans for determining whether the current data rate satisfies athreshold, based upon an analysis of the input signal 68. Alternatively,the means 54 for analyzing input signals can comprise means fordetermining the current data rate based upon an analysis of the inputsignal 68. Alternatively, the means 54 for analyzing input signals cananalyze both input signals 68, 78. The means 54 for analyzing inputsignals is preferably implemented in computer readable program codewritten in any suitable programming language and implemented on ananalog or a digital computer utilizing any suitable operating system.The means 54 for analyzing input signals can also be implemented throughthe use of hardware in the form of a hardwired computer, an integratedcircuit, or a combination of hardware and computer readable programcode.

[0032] The means 56 for providing an adaptive interleave control signalpreferably comprises means for providing the input signal 78 as it isreceived from the SNR monitor 70. Accordingly, the adaptive interleavecontrol signal 58 is preferably equivalent to the received input signal78. Alternatively, the adaptive interleave control signal 58 can takemany forms. The adaptive interleave control signal can be based in-wholeor in-part on one or both of the input signals 68, 78. The adaptiveinterleave control signal 58 can be analog or digital and linear ornon-linear as known to those skilled in the art. Alternatively, theadaptive interleave control signal 58 can be binary such that theadaptive interleave control signal produced is greater than or less thana threshold value based upon one or both of the input signals 68, 78 asknown to those skilled in the art. The means 56 for providing anadaptive interleave control signal is preferably implemented in computerreadable program code written in any suitable programming language andimplemented on an analog or a digital computer utilizing any suitableoperating system. The means 56 for providing an adaptive interleavecontrol signal can also be implemented through the use of hardware inthe form of a hardwired computer, an integrated circuit, or acombination of hardware and computer readable program code.

[0033] Referring now to FIG. 3, a transmission system 100 comprising theadaptive interleaver 20, the transmitter 30, the transmission channel35, the receiver/decoder 40 and a controller 150 according to analternate embodiment is shown. The adaptive interleaver 20, transmitter30, transmission channel 35 and receiver/decoder 40 are all the same asdescribed above.

[0034] The controller 150 preferably comprises a data rate monitor 60, abit error rate monitor 170, means 154 for analyzing input signals andmeans 156 for providing an adaptive interleave control signal. The datarate monitor 60 is the same as described above. The bit error ratemonitor 170 preferably comprises a monitor for determining BER as knownto those skilled in the art. The bit error rate monitor 170 ispreferably coupled with the receiver/decoder 40 and the controller 150.BER is preferably defined as the relative frequency of error bits toreceived bits. The BER is preferably determined though the use of acyclic redundancy code (CRC) in the encoded symbols. A CRC enables a biterror rate monitor to determine when errors in the decoded symbolsoccur. By monitoring the errors identified through the use of the CRCover a period of time, the BER of the system can be determined.Alternatively, BER can be determined through a-variety of othertechniques, and any suitable method of determining BER can be adaptedfor use in the presently preferred system. Averaging many measurementsof BER can be performed to improve the accuracy of the current BERcalculations as known to those skilled in the art.

[0035] The bit error rate monitor 170 preferably generates an inputsignal 178 that varies as a function of the BER Alternatively, the inputsignal 178 can take many forms. The input signal 178 can be basedin-whole or in-part on the BER. The input signal 178 can be analog ordigital and linear or non-linear as known to those skilled in the art.Alternatively, the input signal 178 can be binary such that the inputsignal 178 is greater than or less than a threshold value based upon theBER as known to those skilled in the art. The BER monitor 170 preferablydetermines the BER and continuously generates the input signal 178.Alternatively, the BER monitor 170 can determine the BER and generatethe input signal 178 in a sampled fashion on a random or nonrandombasis.

[0036] The means 154 for analyzing input signals preferably comprisesmeans for determining whether the current data rate exceeds apredetermined threshold, based upon an analysis of the input signal 68.Alternatively, the means 154 for analyzing input signals can comprisemeans for determining the current data rate based upon an analysis ofthe input signal 68. Alternatively, the means 154 for analyzing inputsignals can analyze both of the input signals 68, 178. The means 154 foranalyzing input signals is preferably implemented in computer readableprogram code written in any suitable programming language andimplemented on an analog or a digital computer utilizing any suitableoperating system. The means 154 for analyzing input signals can also beimplemented through the use of hardware in the form of a hardwiredcomputer, an integrated circuit, or a combination of hardware andcomputer readable program code.

[0037] The means 156 for providing an adaptive interleave control signalpreferably comprises means for providing the input signal 178 as it isreceived from the BER monitor 170. Accordingly, the adaptive interleavecontrol signal 158 is preferably equivalent to the received input signal178. Alternatively, the adaptive interleave control signal 158 can takemany forms. The adaptive interleave control signal 158 can be basedin-whole or in-part on one or both of the input signals 68, 178. Theadaptive interleave control signal 158 can be analog or digital andlinear or non-linear as known to those skilled in the art.Alternatively, the adaptive interleave control signal 158 can be binarysuch that the adaptive interleave control signal 158 is greater than orless than a threshold value based upon one or both of the input signals68, 178 as known to those skilled in the art. The means 156 forproviding an adaptive interleave control signal in response to the inputsignals is preferably implemented in computer readable program codewritten in any suitable programming language and implemented on ananalog or a digital computer utilizing any suitable operating system.The means 156 for providing an adaptive interleave control signal inresponse to the input signals can also be implemented through the use ofhardware in the form of a hardwired computer, an integrated circuit, ora combination of hardware and computer readable program code.

[0038] While the controller 50, 150 and adaptive interleaver 20 arepreferably implemented as separate elements as shown in FIGS. 1 and 2,they can alternatively be implemented as a single element comprisingsoftware, hardware or a combination thereof as described herein andknown to those skilled in the art.

[0039] Referring now to FIG. 4, a transmission system 180 comprising theadaptive interleaver 20, the transmitter 30, the transmission channel35, the receiver/decoder 40 and a controller 80 is shown. The adaptiveinterleaver 20, transmitter 30, transmission channel 35 andreceiver/decoder 40 are all the same as described above. The controller80 preferably comprises a signal to noise ratio monitor 72 as describedherein. The signal to noise ratio monitor 72 generates a multiple bitadaptive interleave control signal 74 that preferably varies as afunction of the SNR. The adaptive interleave control signal 74 can bebased in-whole or in-part on the SNR. The adaptive interleave controlsignal 74 can be analog or digital and linear or non-linear as known tothose skilled in the art. Alternatively, the adaptive interleave controlsignal 74 can be binary such that the adaptive interleave control signalproduced is greater than or less than a threshold value based upon theSNR as known to those skilled in the art. The controller 80 ispreferably coupled with to the adaptive interleaver 20 such that theadaptive interleave control signal 74 is supplied directly to theadaptive interleaver 20. The adaptive interleave control signal 74 ispreferably utilized by the adaptive interleaver 20 to control theinterleave depth to generate an adaptively interleaved signal.

[0040] Referring now to FIG. 5, a transmission system 190 comprising theadaptive interleaver 20, the transmitter 30, the transmission channel35, the receiver/decoder 40 and a controller 90 is shown. The adaptiveinterleaver 20, transmitter 30, transmission channel 35 andreceiver/decoder 40 are all the same as described above. The controller90 preferably comprises a bit error rate monitor 172 as describedherein. The bit error rate monitor 172 generates a multiple bit adaptiveinterleave control signal 174 that preferably varies as a function ofthe BER. The adaptive interleave control signal 174 can be basedin-whole or in-part on the BER. The adaptive interleave control signal174 can be analog or digital and linear or non-linear as known to thoseskilled in the art. Alternatively, the adaptive interleave controlsignal 174 can be binary such that the adaptive interleave controlsignal produced is greater than or less than a threshold value basedupon the BER as known to those skilled in the art. The controller 90 ispreferably coupled with the adaptive interleaver 20 such that theadaptive interleave control signal 174 is supplied directly to theadaptive interleaver 20. The adaptive interleave control signal 174 ispreferably utilized by the adaptive interleaver 20 to control theinterleave depth to generate an adaptively interleaved signal.

[0041] Referring now to FIG. 6, a transmission system 200 comprising theadaptive interleaver 20, the transmitter 30, the transmission channel35, the receiver/decoder 40 and a controller 210 is shown. The adaptiveinterleaver 20, transmitter 30, transmission channel 35 andreceiver/decoder 40 are all the same as described above. The controller210 preferably comprises a data rate monitor 202 as described herein.The data rate monitor 202 generates a multiple bit adaptive interleavecontrol signal 204 that preferably varies as a function of the datarate. The adaptive interleave control signal 204 can be based in-wholeor in-part on the data rate. The adaptive interleave control signal 204can be analog or digital and linear or non-linear as known to thoseskilled in the art. Alternatively, the adaptive interleave controlsignal 204 can be binary such that the adaptive interleave controlsignal produced is greater than or less than a threshold value basedupon the data rate. The controller 210 is preferably coupled with theadaptive interleaver 20 such that the adaptive interleave control signal204 is supplied directly to the adaptive interleaver 20. The adaptiveinterleave control signal 204 is preferably utilized by the adaptiveinterleaver 20 to control the interleave depth to generate an adaptivelyinterleaved signal.

[0042] The system shown in FIG. 2 can be used to implement the method300 shown in FIG. 7. The data rate monitor 60 determines the data rate(step 302, FIG. 7) of the transmission system 10. The data rate monitor60 generates an input signal 68 (step 304) that varies as a function ofthe data rate. The signal to noise ratio monitor 70 determines a SNR(step 306) of the system 10. The signal to noise ratio monitor 70generates an input signal 78 (step 308) that varies as a function of theSNR. The controller 50 analyzes the first input signal 68 (step 310) anddetermines whether the data rate exceeds a predetermined threshold. Thecontroller 50 provides an adaptive interleave control signal 58 (step312) in response to the input signals 68, 78.

[0043] The system shown in FIG. 3 can be used to implement the method320 shown in FIG. 8. The data rate monitor 60 determines the data rate(step 322, FIG. 8) of the transmission system 100. The data rate monitor60 generates a first input signal (step 324) that varies as a functionof the data rate. The bit error rate monitor 170 determines a BER (step326) for the transmission system 100. The bit error rate monitor 170generates a second input signal (step 328) that varies as a function ofthe BER. The controller 150 analyzes the first input signal 68 (step330) and determines whether the data rate exceeds a predeterminedthreshold. The controller provides an adaptive interleave control signal(step 332) in response to the input signals 68, 178.

[0044] In a preferred embodiment, the predetermined threshold isdetermined in relation to the data rate. When the data rate is above acertain level, the system cannot afford the decoder the additional timeneeded to de-interleave the interleaved data. Thus, for data rates abovea certain level, interleaving imposes an unacceptable time delay on thetransmissions. Therefore, when the data rate exceeds the predeterminedthreshold, interleaving is preferably disabled. When the controller 50,150 determines that the data rate exceeds the predetermined threshold,the controller 50, 150 preferably generates an adaptive interleavecontrol signal 58, 158 (respectively) that controls the adaptiveinterleaver 20 such that no interleaving is implemented by the adaptiveinterleaver 20. Alternatively, when the data rate exceeds thepredetermined threshold, the controller 50, 150 can cease generating anadaptive interleave control signal such that no interleaving isimplemented by the adaptive interleaver 20. Thus, interleaving is onlyimplemented when the data rate is below a certain level.

[0045] Alternatively, if the data rate is below the predeterminedthreshold, the controller 50, 150 preferably generates an adaptiveinterleave control signal 58, 158 that controls the adaptive interleaver20 such that interleaving is implemented. The adaptive interleavecontrol signal 58, 158 preferably causes the adaptive interleaver 20 toimplement an interleave depth that is proportional to the SNR, BER, datarate or combination thereof. Alternatively, the interleave depth can beinversely proportional to the SNR, BER, data rate or combinationthereof. Alternatively, the adaptive interleave control signal 58, 158can cause the adaptive interleaver 20 to implement a number of differentinterleave depths depending upon the SNR, BER, data rate or combinationthereof. For example, the controller 50, 150 can implement fivedifferent graduated interleave depths in response to the SNR or BER,assuming that the data rate is high enough to allow for suchinterleaving. Each of the different graduated interleave depths isimplemented when the SNR or BER is within a predetermined range ofvalues.

[0046] The system of FIG. 4 can be used to implement the method 340 ofFIG. 9. The signal to noise ratio monitor 72 determines a SNR (step 342)of the transmission system 180. The signal to noise ratio monitor 72generates an adaptive interleave control signal 74 (step 344) thatpreferably varies as a function of the SNR. The adaptive interleaver 20receives the adaptive interleave control signal and preferably adapts aninterleave depth in response to the adaptive interleave control signal74.

[0047] The system of FIG. 5 can be used to implement the method 350 ofFIG. 10. The bit error rate monitor 172 determines a BER (step 352) ofthe transmission system 190. The bit error rate monitor 172 generates anadaptive interleave control signal 174 (step 354) that preferably variesas a function of the BER. The adaptive interleaver 20 receives theadaptive interleave control signal preferably adapts an interleave depthin response to the adaptive interleave control signal 174.

[0048] The system of FIG. 6 can be used to implement the method 360 ofFIG. 11. The data rate monitor 202 determines a data rate (step 362) ofthe system 200. The data rate monitor 202 generates an adaptiveinterleave control signal 204 (step 364) that preferably varies as afunction of the data rate. The adaptive interleaver 20 receives theadaptive interleave control signal and preferably adapts an interleavedepth in response to the adaptive interleave control signal 204.

[0049] It is to be understood that during operation, the interleavedepth implemented by the adaptive interleaver 20 (FIGS. 2, 3, 4, 5 and6) is generally communicated to the receiver/decoder 40 at the other endof the transmission channel 35 as known to those skilled in the art. Ifthe interleave depth is adjusted solely as a function of the data rate,both the adaptive interleaver 20 and the receiver/decoder 40 can monitorthe current data rate, and can synchronize the interleaving depththrough the use of the same interleave depth control rules as known tothose skilled in the art. However, if the SNR or the BER is used todetermine the interleave depth, additional mechanisms can be used toassure that the interleave depth implemented by the adaptive interleaver20 matches the interleave depth of a de-interleaver during the decodingprocess as known to those skilled in the art. Accordingly, the currentinterleave depth being used by the adaptive interleaver 20 can betransmitted to the receiver/decoder 40 for use in the decoding process.The components and methods required to perform such a transmission andsynchronize the encoding and decoding processes are well known to thoseskilled in the art.

[0050] It is to be understood that a wide range of changes andmodifications to the embodiments described above will be apparent tothose skilled in the art and are contemplated. It is therefore intendedthat the foregoing detailed description be regarded as illustrativerather than limiting, and that it be understood that it is the followingclaims, including all equivalents, that are intended to define thespirit and scope of the invention.

I claim:
 1. A controller for an adaptive interleaver in a transmissionsystem comprising a transmission channel, a transmitter coupled with thetransmission channel and a receiver/decoder coupled with thetransmission channel, the controller comprising: a first performanceparameter monitor responsive to the transmission system, the firstperformance parameter monitor operative to generate a first inputsignal; a second performance parameter monitor responsive to thetransmission system, the second performance parameter monitor operativeto generate a second input signal; and means for providing an adaptiveinterleave control signal in response to the first and second inputsignals; wherein the first and second performance parameters areselected from the group consisting of signal to noise ratio, bit errorrate and data rate.
 2. The controller of claim 1, wherein the means forproviding an adaptive interleave control signal in response to the firstand second input signals comprises computer readable program code. 3.The controller of claim 1, wherein the means for providing an adaptiveinterleave control signal in response to the first and second inputsignals comprises hardware.
 4. The controller of claim 1, wherein thetransmission channel comprises a fiber optic channel.
 5. The controllerof claim 1, wherein the transmission channel comprises a conductive wirechannel.
 6. The controller of claim 1, further comprising an adaptiveinterleaver coupled with the controller, the adaptive interleaveroperative to receive the adaptive interleave control signal.
 7. Acontroller for an adaptive interleaver in a transmission systemcomprising a transmission channel, a transmitter coupled with thetransmission channel and a receiver/decoder coupled with thetransmission channel, the controller comprising: a performance parametermonitor responsive to the transmission system, the monitor operative togenerate an adaptive interleave control signal; wherein the performanceparameter is selected from the group consisting of signal to noiseratio, bit error rate and data rate.
 8. The controller of claim 7,wherein the transmission channel comprises a fiber optic channel.
 9. Thecontroller of claim 7, wherein the transmission channel comprises aconductive wire channel.
 10. The controller of claim 1, furthercomprising an adaptive interleaver coupled with the controller, theadaptive interleaver operative to receive the adaptive interleavecontrol signal.
 11. A method for controlling an adaptive interleaver ina transmission system comprising a transmission channel, an adaptiveinterleaver coupled with the transmission channel and a receiver/decodercoupled with the transmission channel, the method comprising the stepsof: determining a first performance parameter of the transmissionsystem; determining a second performance parameter of the transmissionsystem; and providing an adaptive interleave control signal in responseto the first and second performance parameters; wherein the first andsecond performance parameters are selected from the group consisting ofsignal to noise ratio, bit error rate and data rate.
 12. The method ofclaim 11, further comprising the step of analyzing the first performanceparameter.
 13. The method of claim 12, wherein the step of analyzing thefirst performance parameter comprises the step of determining whetherthe first performance parameter exceeds a predetermined threshold.
 14. Amethod for controlling an adaptive interleaver in a transmission systemcomprising a transmission channel, a transmitter coupled with thetransmission channel and a receiver/decoder coupled with thetransmission channel, the method comprising the steps of: determining aperformance parameter of the transmission system; providing an adaptiveinterleave control signal in response to the performance parameter, andtransmitting the adaptive interleave control signal to an adaptiveinterleaver; wherein the performance parameter is selected from thegroup consisting of signal to noise ratio, bit error rate and data rate.15. A controller for an adaptive interleaver in a transmission systemcomprising a transmission channel, a transmitter coupled with thetransmission channel and a receiver/decoder coupled with thetransmission channel, the controller comprising: means for generating afirst input signal as a function of a first performance parameter of thetransmission system; means for generating a second input signal as afunction of a second performance parameter of the transmission system;and means for providing an adaptive interleave control signal inresponse to the first and second input signals; wherein the first andsecond performance parameters are selected from the group consisting ofsignal to noise ration, bit error rate and data rate.
 16. A computerusable medium having computer readable program code embodied therein forcontrolling an adaptive interleaver, the computer readable program codecomprising: computer readable program code means for causing a computerto generate an adaptive interleave control signal in response to a firstinput signal indicative of a first performance parameter and a secondinput signal indicative of a second performance parameter; wherein thefirst and second performance parameters are selected from the groupconsisting of signal to noise ratio, bit error rate and data rate.
 17. Acomputer usable medium having computer readable program code embodiedtherein for controlling an adaptive interleaver, the computer readableprogram code comprising: computer readable program code means forcausing a computer to analyze a first input signal indicative of a firstperformance parameter; and computer readable program code means forcausing a computer to generate an adaptive interleave control signal inresponse to the first input signal and a second input signal indicativeof a second performance parameter; wherein the first and secondperformance parameters are selected from the group consisting of signalto noise ratio, bit error rate and data rate.